And like the engine, if more power output is required, more power energy input is simultaneously required.
If you add electrical load to the alternator, you have to increase power input to the alternator. If the RPM’s are kept constant, the additional power required to match the increased force by the increased electromagnetic fields is supplied by additional torque. This requires additional fuel from the engine. All this additional load has the same inefficiencies of the engine, friction and the alternator so even more fuel energy is consumed than the electrical energy produced.
Your assuming that the injection of hydrogen into combustion chamber has no effect on the engines efficiency.